Need to know the charset of the browser from which the request is coming

I need to know the charset of the browser from which the request is coming for encoding pupose.
I have tried things by getting them in the HTTP request but there i am getting only the accepted charsets,that is set of encodings like (utf-8,shift-jis,iso-8859-1) like this

but i need to know exactly what is the charset of the brower so that i can decode them in to the required format before showing the responce

I am very thank ful if any body helps me in this and Thanks in Advance.